<PRE><B>Question 351969</B>
create 2 equations since there are two unknowns
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Let A=lbs of type 1 grapes
Let B=lbs of type 2 grapes
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weight equation 1:   A+B=14  (together they weight 14 lbs)
Cost equation 2:    0.25A+0.20*B=3.10   (together they cost 3.10)
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multiply equation2 by 100 to eliminate the decimal and work with whole numbers
25A+20B=310
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Solve equation 1 for A:    A=14-B
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Substitute into above equation
25*(14-B)+20B=310
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25*14-25B+20B=310  (distribute 25)
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350-5B=310      (combine and simplify)
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-5B=310-350=-40   (sub 350 from both sides)
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B=-40/-5=8
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subsitute B=8 into A=14-B,  A=6
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Validate the answer of A=6, B=8 by sub stituting into original equation
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0.25A+0.20*B=3.10 
0.25*6+0.2*8=1.5+1.6=3.10  check</PRE>